Opioids, also known as opioid agonists, are a group of active pharmaceutical agents that exhibit opium- or morphine-like properties. More particularly, opioid agonists exhibit some form of opioid receptor activity. Opioids are employed primarily as moderate to strong analgesic agents.
There have been previous attempts in the art to increase the tamper resistance of opioid analgesic dosage forms. Prior approaches to developing tamper resistant dosage forms have included combining an opioid agonist with an opioid antagonist. Particular examples of such combinations include compositions comprising naloxone and morphine or oxymorphone (U.S. Pat. No. 3,493,657 to Lewenstein et al.); methadone and naloxone (U.S. Pat. No. 3,773,955 to Pachter et al.); methadol or acetyl methadol and naloxone (U.S. Pat. No. 3,966,940 to Pachter et al.); oxycodone and naloxone (U.S. Pat. No. 4,457,933 to Gordon et al.); and buprenorphine and naloxone (U.S. Pat. No. 4,582,835 to Lewis et al.).
U.S. Pat. No. 6,228,863 to Palermo et al. discloses an oral dosage form which combines an opioid agonist and an opioid antagonist such that at least two separation steps are required to isolate the agonist.
U.S. Pat. No. 5,935,975 to Rose et al. discloses a method for treating drug dependency by the combined administration of the drug, i.e. the agonist, and an antagonist of the drug.
PCT Publication No. WO 01/58451 entitled “Tamper Resistant Oral Opioid Agonist Formulations,” is directed to decreasing the abuse potential associated with opioid analgesic dosage forms by the inclusion of a sequestered opioid antagonist in an opioid agonist dosage form.
In addition, it is known in the pharmaceutical art to prepare oral dosage forms which provide for controlled release of therapeutically active agents. Such controlled release compositions are used to delay absorption of at least a portion of the dose of the agent until it has reached certain portions of the gastrointestinal tract. Such controlled release of the agent serves to maintain a desired concentration of the agent in the blood stream for a longer duration than would occur if conventional immediate or rapid release dosage forms were to be administered.
Over the years, several different methods of preparing controlled release pharmaceutical dosage forms have been suggested, including, for example, extrusion, granulation, coating beads and the like.
There remains a need in the art for improved tamper resistant dosage forms and improved techniques for their preparation.